Fuel Injector Nozzle Spring Biasing for Sliding Phase Control
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Solution Overview
Problem
In fuel injectors, manufacturing tolerances and operating conditions cause the needle valve to become misaligned with the bore, leading to an unpredictable sliding phase during opening and closing, which complicates close loop control and requires unreliable coatings with resistive piezo material to monitor the needle position accurately.
Innovation Solution
A spring assembly is radially compressed between the needle and the bore, ensuring a reproducible sliding phase with a known duration, allowing for precise control of the fuel injector by maintaining electrical isolation and using various spring configurations such as coil springs, collar members, or spherical pushing members to bias the needle radially.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the needle valve is designed to be coaxial with the bore, then the sliding phase should be minimized, but manufacturing tolerances and operating conditions cause misalignment leading to an unpredictable sliding phase
Solution Approach 1:
The spring assembly is pre-installed and compressed between the needle valve and the bore, creating a predetermined radial bias force that ensures the needle maintains proper alignment with the bore throughout operation. This preliminary mechanical action compensates for manufacturing tolerances and prevents misalignment before it can cause unpredictable sliding phases.
Solution Approach 2:
The spring assembly dynamically adjusts the radial position of the needle valve by applying a continuous biasing force, changing the operational parameters of the needle-bore interface. This ensures consistent contact conditions and predictable sliding phase duration despite variations in manufacturing tolerances or operating conditions.
2Measurement precision
If resistive piezo material coating is applied to monitor needle position continuously, then measurement precision is improved, but device complexity and reliability are worsened due to coating durability and signal stability issues
Solution Approach 1:
The invention extracts the monitoring function from complex resistive piezo material coatings and replaces it with a simple mechanical spring assembly that provides inherent, coating-free position indication. The spring's physical presence and force application serve as the monitoring mechanism, eliminating the need for sophisticated coatings and complex signal processing systems.
Solution Approach 2:
The spring assembly uses simple, inexpensive mechanical components instead of expensive, fragile piezoelectric coatings. The spring is a robust, replaceable mechanical element that is more reliable and easier to manufacture than delicate electronic coatings, providing a cost-effective and durable solution.
3Stability of the object's composition
If the spring assembly radially compresses the needle against the bore, then the sliding phase becomes reproducible and predictable, but the needle position monitoring complexity increases
Solution Approach 1:
The spring assembly serves multiple functions simultaneously: it provides radial biasing to ensure proper needle alignment, maintains consistent contact conditions for predictable sliding phase, and acts as a mechanical reference for position monitoring. This multi-functionality reduces the need for separate components and simplifies the overall system.
Solution Approach 2:
The spring assembly is self-regulating, automatically adjusting the needle's radial position based on operating conditions. The spring's elastic properties allow it to self-compensate for variations in fuel pressure, temperature, and wear, maintaining consistent sliding phase characteristics without external intervention or complex control systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a consistent and reproducible sliding phase duration, independent of needle rotation and misalignment, allowing for accurate close loop control of the fuel injector, eliminating the need for unreliable coatings and ensuring reliable command signals.
Implementation Method 1
A spring assembly is radially compressed between the needle and the bore
Data Source
Figure 1
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AI summary
ABSTRACT OF THE DISCLOSURE A nozzle assembly (26) of a fuel injector (10) comprises a nozzle body (28) defining an inner bore extending along a main axis (X), said bore forming at a first extremity a tapered fixed valve seat (42) adapted to receive in sealing contact a complementary tapered needle seating face (52) of a needle valve slidably arranged in the bore, and adapted to translate along the main axis (X) between a closed position where the needle seating face (52) is in sealing contact with the fixed valve seat (42) and, a fully open position where the needle seating face is lifted away from the fixed valve seat. The nozzle assembly (26) is further provided with a spring assembly radially compressed between the needle and the bore so that in use, when beginning a lift of the needle (36) from the closed position toward the open position, the tapered needle seating face (52) slides and remains in contact against the fixed valve seat (52) instead of coaxially separating immediately.